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Old   September 19, 2002, 10:58
Default Strouhal No
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Ashvin
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I need to know where should be the location of probe for calculating the vortex shedding frequency and what parameter should be considered for calculating the time-period of vortex shedding
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Old   September 19, 2002, 11:55
Default Re: Strouhal No
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JONGDAE KIM
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1. Depends on your probe, the locations should be different. For Hot-wire, it should be located in the low turbulence region.

2. About 30 times (of the body size) downstream, you can get shedding frequency from the measured data.

3. Estimate the approximate shedding frequency of you model and decide the sampling frequency.
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Old   September 20, 2002, 03:22
Default Re: Strouhal No
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Jan Rusås
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If LDA is used for the measuring is there requirement to where it should be measured. I need to find the shedding frequency in a tube bank, and I want to measure between the tubes. The distance between the tubes is 1 diameter. Jan
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Old   September 20, 2002, 10:14
Default Re: Strouhal No
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JONGDAE KIM
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1. LDA is prohibitive to measure velocity very close to the cylinder.

2. Depends on the Reynolds number, the flow could be three dimensional. Since the distance bet. cylinders are 1-D, the wake might be almost two dimensional. That means you don't need to measure the properties of streamwise coherent structures.

3. Due to the interference, it might be possible that the shedding frequency changes depending on the measuring positions.

4. At some positions, double or tripple frequency is dominant in the power spectral density function.

Kim
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